Industrial metal working machinery is widely employed to accomplish such precision operations as internal grinding wherein a smoothly finished surface worked to close tolerances is required. Such machinery typically comprises a workhead having a workholder or chuck and a wheelhead carrying the metal working tool; e.g. a grinder wheel. In addition, the machinery typically comprises first and second slide assemblies which provide the necessary longitudinal and lateral displacement capabilities between the work holder and the wheel spindle. As is well known, the longitudinal displacement is taken along an axis aligned with the workholder and wheelhead axes whereas lateral displacement is taken along an axis perpendicular to the wheel spindle axis and permits the wheel to be fed radially into engagement with the workpiece. An example of a grinder machine having two slide assemblies is shown in U.S. Pat. No. 2,952,949 issued Sept. 20, 1969 to Paul Maker.
One of the inherent difficulties or problems with a machine having two slides is the realization of high machine stiffness or rigidity under load. The lateral slide introduces position variations by virtue of its mechanical compliance. As is well known, compliance in bearings and other mechanical components which are involved in the implementation of the slide assembly can be minimized by the use of complex and precision parts, preloading and other approaches, but all such solutions add cost and complexity to the machine. Accordingly, a machine having two slide assemblies is typically less stiff than a single slide machine.